Kitab-i-Iqan — Paragraph 200
Source (Persian)
مثل اينکه مذکور شد در سؤال از اهلّه که از سيّد وجود نمودند و آن حضرت به امر الهی جواب فرمود که "هِيَ مَوَاقِيتُ للنّاسِ." بعد از استماع، نفی علم از آن حضرت نمودند.
Translation
For instance, when Muhammad, the Lord of being, was questioned concerning the new moons, He, as bidden by God, made reply: “They are periods appointed unto men.” Thereupon, they that heard Him denounced Him as an ignorant man.